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1015. Bowren, K.E. (ed.).. 1986. Soil improvement with legumes.. Saskatchewan Agriculture, Soils and Crops Branch.This excellent publication summarizes research over the past 40 years pertaining to the use of legumes for soil improvement in Saskatchewan. The role of legumes in maintaining soil nitrogen was crucial prior to available fertilizer. But their value extends beyond their nitrogen contribution to the improvement of soil physical properties. One study found the tillage draft requirement to be up to one-third lower where legumes had been a regular part of the rotation. The positive effects of alfalfa were measured for over ten years in a series of wheat crops compared to plots with no alfalfa. Over 17 years, the average grain yield from a wheat-wheat/clover-clover green manure rotation with no fertilizer were 30% higher that a wheat-wheat-fallow rotation with fertilizer. Moisture depletion by legumes is the biggest hurdle to their use in very dry areas. Adequate fertility for the legumes is necessary to maximize their benefit. Use of selected Rhizobium strains can improve nitrogen fixation, especially on acid soils. Several varieties of sweetclover are mentioned with adaptation to forage or green manure use. The booklet has numerous color photos and many data tables and figures.

6248. Sievers, F.J. and H.F. Holtz. 1922. The silt loam soils of eastern Washington and their management.. WA Agr. Expt. Sta. Bull. #166.A broad treatment of agronomy and soil management during 39 years of cropping 22% N and 35% OM has been lost. T: Comparison of nitrogen content of virgin soil and soil cropped 30 years. Organic carbon in virgin soil and soil cropped 30 years. Straw vs. nitrate development in Palouse silt-loam. High N residue as supplement to straw in nitrate development. Effects of manure on N and C in Palouse silt loam, 18 years of results. Effect of legumes on N and C.